ZOOLFUN

• Mitochondria generate most of the cell's supply of adenosine triphosphate (ATP), which is the chemical energy currency of cells.
• Plasma Membrane:

  • Selective barrier allowing passage of oxygen, nutrients, and waste
• Nucleus:

  • Contains most of the cell's genes
  • Nuclear envelope encloses the nucleus, separating it from the cytoplasm
  • Pores regulate entry and exit of molecules
  • Nuclear Lamina maintains nucleus shape
  • Chromosomes are condensed DNA during mitosis
  • Chromatin is DNA and proteins together
  • Nucleolus is the site of ribosomal RNA synthesis
• Ribosomes:

  • Complexes made of ribosomal RNA and protein
  • Carry out protein synthesis in cytosol (free ribosomes) and on the outside of the endoplasmic reticulum or nuclear envelope (bound ribosomes)
• Endoplasmic Reticulum:

  • Accounts for more than half of the total membrane in many eukaryotic cells
  • Smooth ER lacks ribosomes
  • Rough ER surface is studded with ribosomes
  • Functions of Smooth ER: synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores calcium ions
  • Functions of Rough ER: has bound ribosomes that secrete glycoproteins, distributes transport vesicles, serves as a membrane factory for the cell
• Golgi Apparatus:

  • Consists of flattened membranous sacs called cisternae
  • Modifies products of the ER, manufactures certain macromolecules, sorts and packages materials into transport vesicles
• Lysosome:

  • Membranous sac of hydrolytic enzymes that digest macromolecules
  • Enzymes work best in acidic environment
  • Made by rough ER and processed in the Golgi apparatus
  • Can engulf another cell by phagocytosis, recycle the cell's organelles and macromolecules through autophagy
• Mitochondria:

  • Found in nearly all eukaryotic cells
  • Have smooth outer membrane and inner membrane folded into cristae
  • Cristae provide large surface area for ATP synthesis enzymes
• Cytoskeleton:

  • Network of fibers that organizes cell structures and activities
  • Composed of 3 types of molecular structures
  • Supports the cell, maintains its shape, and produces motility
  • Vesicles can travel along cytoskeleton tracks
• Centrosome:

  • Microtubules grow out from centrosome near the nucleus in animal cells
  • Contains centrioles with microtubule triplets
  • Control beating of flagella and cilia
  • Cilia and Flagella share a common structure with microtubules, basal body, and motor protein dynein
• Metabolism:

  • Totality of an organism's chemical reactions
  • Catabolic pathways release energy by breaking down complex molecules
  • Anabolic pathways consume energy to build complex molecules
  • Bioenergetics studies how organisms manage energy resources
  • Energy can be converted from one form to another
• Enzymes:

  • Speed up metabolic reactions by lowering energy barriers
  • Catalysts that are not consumed by the reaction
  • Lower activation energy needed to start a chemical reaction
• Cellular Respiration:

  • Process to release energy from digested food (glucose)
  • Involves glycolysis, citric acid cycle, and oxidative phosphorylation
  • ATP is the energy source for all cells
  • Oxidative phosphorylation generates most ATP
  • Glycolysis breaks down glucose into pyruvate
• In the presence of oxygen, pyruvate enters the mitochondrion in eukaryotic cells to complete the oxidation of glucose
• Before the citric acid cycle can begin, pyruvate must be converted to acetyl Coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle
• Without oxygen, the electron transport chain will cease to operate
• Glycolysis couples with anaerobic respiration or fermentation to produce ATP in the absence of oxygen
• Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen
• Anaerobic respiration uses an electron transport chain with a final electron acceptor other than oxygen, such as sulfate
• Fermentation uses substrate-level phosphorylation instead of an electron transport chain to generate ATP
• The citric acid cycle has eight steps, each catalyzed by a specific enzyme
• NADH and FADH2 produced by the citric acid cycle relay electrons extracted from food to the electron transport chain
• Following glycolysis and the citric acid cycle, NADH and FADH2 account for most of the energy extracted from food
• NADH and FADH2 donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation
• Proteins are digested to amino acids, where amino groups can feed glycolysis or the citric acid cycle
• Fats are digested to glycerol (used in glycolysis) and fatty acids (used in generating acetyl CoA)
• Cell division is the ability of organisms to produce more of their own kind and is based on the reproduction of cells
• In unicellular organisms, division of one cell reproduces the entire organism
• Multicellular eukaryotes depend on cell division for development from a fertilized cell, growth, and repair
• Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division
• Most cell division results in daughter cells with identical genetic information, DNA
• Meiosis is a special type of division that can produce sperm and egg cells
• All the DNA in a cell constitutes the cell's genome
• A genome can consist of a single DNA molecule or a number of DNA molecules
• DNA molecules in a cell are packaged into chromosomes
• Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein that condenses during cell division
• Somatic cells have two sets of chromosomes, while gametes have half as many chromosomes as somatic cells
• In preparation for cell division, DNA is replicated and the chromosomes condense
• Each duplicated chromosome has two sister chromatids attached along their lengths by cohesins